Influence of antenna configuration on achievable throughput in real indoor propagation environment for 2-by-2 single-user MIMO in LTE-advanced uplink

This paper clarifies the influence of the antenna configuration on the achievable throughput in a real indoor propagation environment employing 2-by-2 single-user (SU) multiple-input multiple-output (MIMO) in the Long Term Evolution (LTE)-Advanced uplink with single carrier-based radio access. For four antenna configurations, the achievable throughput performance with adaptive modulation and coding (AMC) and hybrid automatic repeat request (HARQ) is evaluated under line-of-sight (LOS) and non-LOS (NLOS) conditions using the implemented LTE-Advanced transceiver. Experimental results show that under LOS conditions, Rank-2 MIMO spatial multiplexing is invaluable in improving the achievable throughput because the restriction on the mobile station (MS) transmission power in an indoor environment is not so severe due to a small cell size compared to that in a field environment. The results also show that when a cross-polarized antenna configuration is employed, the location probability for achieving throughput greater than 200 Mbps is approximately 95%. We confirm that under NLOS conditions, Rank-1 closed-loop transmit diversity with precoding is effective in enhancing the coverage in an indoor environment. Furthermore, we clarify that high throughput performance is obtained irrespective of the MS or base station (BS) antenna separation since the appropriate precoding vector (PV) is selected for each antenna configuration.